144 lines
4.7 KiB
Markdown
144 lines
4.7 KiB
Markdown
---
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title: Common Array Methods
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localeTitle: Métodos comuns de matriz
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---
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## Métodos comuns de matriz
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Ruby Arrays formam uma base fundamental na programação em Ruby, e na maioria das linguagens de fato. É usado tanto que seria benéfico conhecer e até memorizar alguns dos métodos mais usados para matrizes. Se você quiser saber mais sobre Ruby Arrays, temos [um artigo sobre eles](https://guide.freecodecamp.org/ruby/ruby-arrays) .
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Para os propósitos deste guia, nosso array será o seguinte:
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\`\` \`ruby array = \[0, 1, 2, 3, 4\]
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```
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#### .length
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The .length method tallies the number of elements in your array and returns the count:
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```
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rubi array.length => 5
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```
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#### .first
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The .first method accesses the first element of the array, the element at index 0:
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```
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rubi array.first => 0
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```
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#### .last
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The .last method accesses the last element of the array:
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```
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rubi array.last => 4
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```
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#### .take
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The .take method returns the first n elements of the array:
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```
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rubi array.take (3) => \[0, 1, 2\]
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```
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#### .drop
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The .drop method returns the elements after n elements of the array:
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```
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rubi array.drop (3) => \[3, 4\]
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```
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#### array index
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You can access a specific element in an array by accessing its index. If the index does not exist in the array, nil will be returned:
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```
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rubi matriz \[2\] => 2
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matriz \[5\] => nulo
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```
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#### .pop
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The .pop method will permantently remove the last element of an array:
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```
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rubi array.pop => \[0, 1, 2, 3\]
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```
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#### .shift
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The .shift method will permantently remove the first element of an array and return this element:
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```
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rubi array.shift => 0
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array => \[1, 2, 3, 4\]
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```
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#### .push
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The .push method will allow you to add an element to the end of an array:
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```
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rubi array.push (99) => \[0, 1, 2, 3, 4, 99\]
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```
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#### .unshift
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The .unshift method will allow you to add an element to the beginning of an array:
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```
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array = \[2, 3\] array.unshift (1) => \[1, 2, 3\]
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```
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#### .delete
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The .delete method removes a specified element from an array permanently:
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```
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rubi array.delete (1) => \[0, 2, 3, 4\]
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```
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#### .delete_at
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The .delete_at method allows you to permanently remove an element of an array at a specified index:
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```
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rubi array.delete\_at (0) => \[1, 2, 3, 4\]
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```
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#### .reverse
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The .reverse method reverses the array but does not mutate it (the original array stays as is):
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```
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rubi array.reverse => \[4, 3, 2, 1, 0\]
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```
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#### .select
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The .select method iterates over an array and returns a new array that includes any items that return true to the expression provided.
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```
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rubi array = \[1, 2, 3, 4, 5, 6, 7, 8, 9, 10\] array.select {| number | número> 4} => \[5, 6, 7, 8, 9, 10\] array => \[5, 6, 7, 8, 9, 10\]
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```
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#### .include?
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The include? method checks to see if the argument given is included in the array:
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```
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rubi array = \[1, 2, 3, 4, 5\] => \[1, 2, 3, 4, 5\] array.include? (3) = verdadeiro
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#### .aplainar
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O método flatten pode ser usado para obter uma matriz que contém matrizes aninhadas e criar uma matriz unidimensional:
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\`\` \`ruby array = \[1, 2, \[3, 4, 5\], \[6, 7\]\] array.flatten => \[1, 2, 3, 4, 5, 6, 7\]
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```
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#### .join
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The .join method returns a string of all the elements of the array separated by a separator parameter. If the separator parameter is nil, the method uses an empty string as a separator between strings.
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```
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rubi array.join => "1234" array.join (" _") => "1_ 2 _3_ 4"
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```
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#### .each
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The .each method iterates over each element of the array, allowing you to perform actions on them.
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```
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rubi array.each do | element | coloca elemento fim => 0 1 2 3 4
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```
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#### .map
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The .map method is the same as the .collect method. The .map and .collect methods iterate over each element of the array, allowing you to perform actions on them. The .map and .collect methods differ from the .each method in that they return an array containing the transformed elements.
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```
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rubi array.map {| elemento | elemento \* 2} coloca elemento fim => 0 2 4 6 8
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```
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#### .uniq
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The .uniq method takes in an array containing duplicate elements, and returns a copy of the array containing only unique elements--any duplicate elements are removed from the array.
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```
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rubi array = \[1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 6, 7, 8\] array.uniq => \[1, 2, 3, 4, 5, 6, 7, 8\]
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```
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#### .concat
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The .concat method appends the elements from an array to the original array. The .concat method can take in multiple arrays as an argument, which will in turn append multiple arrays to the original array.
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```
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rubi array = \[0, 1, 2, 3, 4\] array.concat (\[5, 6, 7\], \[8, 9, 10\]) => \[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10\] \`\` \`
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## Mais Informações
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* [Documentação do Ruby Array](http://ruby-doc.org/core-2.5.1/Array.html) |